title: Variation in M protein production among Streptococcus pyogenes strains according to emm genotype.
abstract: M protein is an important virulence determinant in Streptococcus pyogenes, but the amounts of M protein in various strains of the species remain to be elucidated. To assess the amount of M protein in strains of each emm genotype, dot blot analysis was performed on 141 clinically isolated strains. Among the cell membrane-associated proteins, M protein was present in greater quantities in the emm1, 3, and 6 strains than in the other emm strains. In addition three strains, one each of the emm1, 3, and 6 types, showed prolific M protein production (M protein-high producers). These three emm genotypes are frequently isolated in clinical practice. Sequencing of the csrRS gene, one of the two-component signal transduction systems implicated in virulence, was performed on 25 strains bearing different amounts of M protein. CsrS mutations, in contrast to CsrR protein, were detected in 11 strains. The M protein-high producer strain of emm1 type carried two amino acid substitutions, whereas the other three emm1 strains carried only one substitution each. The M protein-high producer expressed its emm gene more strongly than the corresponding M protein-low producer did according to TaqMan RT-PCR. These observations suggest that the accumulation of amino acid substitutions in CsrS protein may contribute, at least in part, to the large amount of M protein production seen in several emm genotypes.
authors.affiliation: Department of Microbiology and Medical Zoology Aichi Prefectural Institute of Public Health, Aichi, Japan. masakado_matsumoto@pref.aichi.lg.jp
authors.forename: Masakado
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Masahiro
authors.initials: M
authors.lastname: Suzuki
authors.forename: Kaoru
authors.initials: K
authors.lastname: Hirose
authors.forename: Reiji
authors.initials: R
authors.lastname: Hiramatsu
authors.forename: Hiroko
authors.initials: H
authors.lastname: Minagawa
authors.forename: Masaaki
authors.initials: M
authors.lastname: Minami
authors.forename: Ichiro
authors.initials: I
authors.lastname: Tatsuno
authors.forename: Akira
authors.initials: A
authors.lastname: Okamoto
authors.forename: Michio
authors.initials: M
authors.lastname: Ohta
authors.forename: Tadao
authors.initials: T
authors.lastname: Hasegawa
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D000942:Antigens, Bacterial / Q000096:biosynthesis* / Q000235:genetics*; D001425:Bacterial Outer Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics*; D020869:Gene Expression Profiling; D005838:Genotype; D006801:Humans; D015151:Immunoblotting; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D011494:Protein Kinases / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013290:Streptococcal Infections / Q000382:microbiology; D013297:Streptococcus pyogenes / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D037521:Virulence Factors / Q000096:biosynthesis* / Q000235:genetics*
chemical_list: D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; C432143:CsrR protein, Streptococcus pyogenes; D012097:Repressor Proteins; D037521:Virulence Factors; C014689:streptococcal M protein; D011494:Protein Kinases; C432144:CsrS protein, bacteria